Toxicity investigation of aqueous extract from different parts of ricinus communis against culex pipiens larvae

Background: Knowing that chemical insecticides used in pest control have become harmful to the environment and public health, the search for effective and safely alternatives has become a necessity today. Among alternative means, toxic plant extracts are actively sought. Objective: This article aims to highlight the efficacy of the aqueous extracts of Ricinus communis by investigating its toxicity against larvae of the mosquito. Methods: The toxicity of the aqueous extracts from the different parts of the plant Ricinus communis (leaves, stems and roots) was studied on Culex pipiens larvae. Percentages of larval mortality were analyzed by the A NOVA1 statistical test. Mortality rates and lethal concentrations (LC50 and LC90) were determined after 24 hours of exposure to several aqueous extracts. Results: Results obtained in laboratory indicated that all parts of the plant are toxic but to different degrees. The importance of toxicity based on the LC50 and LC90 values are arranged in a decreasing order: young leaves (LC50 = 195 mg/L; LC90 = 398 mg/L) > Roots (LC50 = 224 mg/L; LC90 = 417 mg/L) > Stems (LC50 = 398 mg/L; LC90 = 1820 mg/L). The active substances contained in the extracts and which are not yet identified have a different distribution in the plant. The larvicidal activity of these aqueous extracts is relatively comparable to those obtained in other works using organic extracts and essential oils of medicinal plants. Conclusion: The results of this study suggest that the aqueous extracts of the Ricinus communis leaves, stems and roots have larvicidal properties and they could be used as a means in mosquito larvae control. keyswords: Larvicidal activity, mosquito larvae, mosquito control, lethal concentrations .